The chick pineal gland and retina synthesize melatonin in a circadian rhythm with high levels during the night. The rhythmic changes in the hormone production result predominantly from the fluctuation in the activity of serotonin N-acetyltransferase (AA-NAT), a penultimate and key regulatory enzyme in melatonin biosynthesis. The aim of this study was to analyze the effects of an acute and prolo...

The pineal organ (or pineal) of a teleost fish, the pike, contains typical (cone-like) and modified photoreceptor cells. Both are involved in indole metabolism, including melatonin production. How photoperiod controls melatonin biosynthesis in organs containing mainly photoreceptor cells, remains unclarified. To tackle this question we have used cultured pike pineal organs to investigate the va...

The New Zealand White rabbit provides a widely used animal model for the human acetylation polymorphism, which confers marked interindividual variation in the effect and toxicity of numerous drugs, chemicals, and potential carcinogens. The relationship of a recently isolated cDNA clone, designated rnat, to genetically polymorphic arylamine N-acetyltransferase (NAT; acetyl-CoA:arylamine N-acetyl...

In commemoration of Aaron Lerner’s isolation and chemical identification of the indoleamine hormone N-acetyl-5-methoxytryptamine (better known as melatonin) the Institute for Hormone and Fertility Research at the University of Hamburg called together melatonin researchers, both established and newcomers, to discuss this interesting molecule and its impact on basic and clinical research. In addi...

Ž . Pineal melatonin synthesis serotonin TM N-acetylserotonin TM melatonin is severely compromised in most inbred strains of mice, in Ž . many cases because serotonin is not acetylated by serotonin N-acetyltransferase arylalkylamine N-acetyltransferase, AANAT . We have found that in the C57BLr6J strain, AANAT mRNA encodes a severely truncated AANAT protein, because a pseudo-exon containing a st...

Sleep is an evolutionarily conserved behavioral state whose regulation is poorly understood. A classical model posits that sleep is regulated by homeostatic and circadian mechanisms. Several factors have been implicated in mediating the homeostatic regulation of sleep, but molecules underlying the circadian mechanism are unknown. Here we use animals lacking melatonin due to mutation of arylalky...

Arylalkylamine N-acetyltransferase (AANAT) catalyzes the transfer of an acetyl group from acetyl coenzyme A (AcCoA) to arylalkylamines, including indolethylamines and phenylethylamines. Multiple aanats are present in teleost fish as a result of whole genome and gene duplications. Fish aanat1a and aanat2 paralogs display different patterns of tissue expression and encode proteins with different ...

The melatonin rhythm-generating enzyme, arylalkylamine N-acetyltransferase (AANAT) is known to have recognizable ancient homologs in bacteria and fungi, but not in other eukaryotes. Analysis of new cDNA and genomic sequences has identified several additional homologs in other groupings. First, an AANAT homolog has been found in the genome of the cephalochordate amphioxus, representing the oldes...